The coagulation system is a cascade of complex, interacting steps, that can selectively be inhibited in distinct ways. Thus, various therapeutic options are offered, concerning primary hemostasis, which results in formation of a platelet-rich thrombus, as well as secondary hemostasis, resulting in fibrin formation. For patients with coronary artery disease, who have to undergo percutaneous coronary intervention (PCI), a sufficient anticoagulant strategy is essential for prevention of ischemic events, due to the activated state of the coagulation system of these patients. Next to antiplatelet therapy, unfractionated heparin (UFH) is a well-established concomitant intravenous therapy during PCI. Also low-molecular-weight heparins (LMWH) are increasingly used in this setting due to their favorable pharmacodynamic properties. The exact value of these substances in comparison to UFH is not completely evaluated yet.